Forensic psychology: genetic and neural explanations/biological explanations for offending Flashcards
Define genetic explanations
The DNA a person inherits from their parents may give them a predisposition to criminal behaviour.
Who researched candidate genes?
Tiihonen et al (2014)
Describe the MAOA gene
Produces the enzyme MonoAmine Oxidase A - breaks down neurotransmitters specifically serotonin, dopamine and noradrenaline.
What does research into candidate genes show?
- Tiihonen et al (2014)
- Genetic analysis of 800 offenders
- Abnormalities in MAOA and CDH13 genes
- 5-10% of serial violent crimes in Finland linked to these genotypes.
Describe the role of adoption studies.
If an individual shares traits with the adoptive family this must be nurture as there is no biological connection.
Who researched adoption studies?
Crowe et al (1972)
What do adoption studies show?
- Crowe et al (1972)
- Having biological parents involved in criminal behaviour = 50% risk of having a criminal record by aged 18 compared to 5% in the general population.
Describe twin study findings
Christiansen (1977 Denmark)
- 3500 twin pairs in males, mz concordance = 35% compared to 13% in DZ
- Data suggesting both behaviour and predisposing traits are inherited.
Who conducted twin studies?
Christiansen (1977, Denmark)
What does the diathesis stress model suggest?
A biological predisposition to criminal behaviour could be triggered by environmental factors.
What do neural explanations focus on?
Neural (e.g. prefrontal cortex) differences in offenders and non-offenders.
Name associated with neural explanations
Raine et al.
What did Raine et al report?
- Reported several brain imaging studies
- Reduced activity + 11% reduction in grey matter in the prefrontal cortex consistent with APD
Who researched mirror neurons as a neural explanation?
Keysers et al (2011)
Describe research into mirror neurons.
Criminals empathy reaction was activated only when they were specifically asked to empathise (it should switch on by default)
- consistent with APD
Evaluation points for genetic explanations
+ Support for diathesis stress
- Problems with twin studies
- problems with adoption studies
+ Support for diathesis stress model
- Mendick et al studied over 13000 adoptees
- when neither biological or adoptive parents had convictions 13.5% adoptees did
- 20% when either biological parent did and 25% when both sets did
- Role of inheritance and environment linked
- Problems with twin studies
- Assume equal environments as twins are raised together
- Especially in MZ twins: parents treat them more similarly impacting behaviour
- Could be higher CR as treated same rather than genetics.
- Problems with adoption studies
- Hard to separate genetic and environmental influences due to late adoptions and adoptees maintaining regular contact with biological parents.
Evaluating neural explanations
+ Brain evidence
- Other factors linked to APD and offending
- Biological reductionism
+ Brain evidence supporting link between crime + frontal lobe
- Kandel and Freed
- reviewed evidence of frontal lobe damage and antisocial behaviour
- Damage was linked to impulsive behaviour, emotional instability + inability to learn from mistakes
- Brain damage may be a causal factor in offending behaviour
- Other factors linked to APD and offending
- Farrington et al
- Studied males who scored highly on psychopathy
- Identified risk factors e.g. raised by convicted parents, physical neglect
- Neglect may result in neural diffs e.g. reduced frontal lobe activity due to trauma (Rauch et al)
Biological reductionism
- crime too complex to reduce to a genetic and neural level
- Hard to disentangle all possible influences
- Twin studies never have 100% CR
